This invention pertains to drives for data carrying disk assemblies and more particularly to a recirculating airflow system for such drives.
A common problem in magnetic disk drives is the sweeping of particulate matter from the data transfer surfaces. Since the transducer or slider carrying the transducer flies on an air bearing with a thickness measured in millionths of an inch, a particle having a dimension of only one micron is several times the air bearing thickness. Particles may be generated during manufacture despite clean room conditions, may be carried by air drawn into the disk enclosure, may occur through leakage past seals. Drive components exposed within the enclosure constitute another source of particles, particularly the head and disk which contact during start and stop operations. Most disk drives are now enclosed with filtered air passed through a recirculating path to limit the amount of air introduced into the enclosure to that resulting from changing conditions of temperature and pressure which can be channeled through a breather filter to entrap airborne particles.
Another source of particulate matter problems is the permanent magnets associated with actuators or drive motors. The permanent magnets and associated magnetic circuits are coated with a urethane compound to captivate magnetic particles and prevent them from getting into the airflow path. However, the possible introduction of such particles is a hazard not only to the aerodynamics of the slider carrying the transducer, but also may erase data from the surface of the disk media.